Use of industrial by-products as sorbents for the removal of lanthanides in contaminated waters

Abstract

One of the techniques used for the remediation of contaminated water is the use of sorbents. In these techniques, the sorbents retain the contaminants from the water. One of the most common sorbents is the activated charcoal. It is an effective commercial sorbent. However, there are some greener, cheaper and equally effective alternatives that might be investigated. For this reason, this project evaluates the efficacy of some materials as sorbents for pollutants, concretely lanthanides . The materials studied include different biochars and a by-product that comes from the metallurgical industry. A previous study1 showed a high efficiency of the studied materials for the sorption of lanthanides (Sm, La, Lu) at a single concentration of 0.05 meq/L. The present study aims to keep going in that direction by doing more experiments to obtain additional information about these materials as sorbents. In this work, it has been evaluated the sorption capacity (sorption percentage and solid-liquid distribution coefficient) of the target materials and of a commercial activated charcoal, all tested at different samarium concentrations in water. This test allows us to see until which contaminant concentration is the material efficient as a sorbent. It has also been tested the desorption of Sm from these materials at the different Sm concentrations, since a good sorbent needs to have a low desorption as well as a good retention of the contaminant. Finally, some information about the existing mechanisms in the sorption process were derived form the sorption-desorption experiments. The obtained results show a very good efficacy of the materials for the sorption of Sm until arriving at high concentrations, and as well as, low desorption. Biochars are very good sorbents, as they only sature at very high concentrations that are not common in environmental situations. An exception was the biochar obtained from sugarcane bagasse, that showed worse results. The coal fines material, which is a by-product of the metallurgical industry, showed a similar behaviour to a studied commercial activated charcoal. It showed a 100% of sorption in the hole concentration range tested . This confirms that the materials studied can be an environmentally friendly, economical and equally effective alternative to the commercial activated charcoal. Keywords: Biochars,